Michael "Jim" Delligatti, a Pittsburgh-based franchisee who opened his first McDonald’s restaurant in 1957, died at his home surrounded by family on Monday. He was 98.

Mr Delligatti said he wanted to offer a bigger burger when he invented the chain’s signature sandwich of two all-beef patties, "special sauce", lettuce, cheese, pickles and onions on a sesame seed bun.

The result garnered instant success and was introduced to his 47 outlets before it went national in 1968.

Since then McDonald’s has sold billions of Big Macs in more than 100 countries.

Mr Delligatti headed M&J Management, a four-generation family business and McDonald's franchise organisation for more than 60 years.

Ann Dugan, a former assistant dean of the University of Pittsburgh's Katz School of Business, said: “In franchising, there's always this set playbook and you have to follow it. Jim saw an opportunity to go outside the playbook because he knew the customer.

"He persevered and (McDonald's) listened, and the rest is history."

Mr Delligatti also helped to introduce breakfast service at McDonald's to feed hungry steelworkers on their way home from overnight shifts in the mills, his family said.

He is survived by his wife Ellie, two sons, five grandchildren and eight great-grandchildren.